Vacuum apparatus



Aug. 20, 1946; V

-K. C. D. HICKMAN VACUUM APPARATUS Filed April 17, 1945 2 Sheets-Sheet l KENNETH 0.1 HICKMAN INVENTOR ATTORNEY N A M K m H n c K VACUUM APPARATUS Filed April 17, 1945 2 Sheets-Sheet 2 FIG FIG. 5

C. D. HICKJWAN INVENTOR A TTORNE Y the liquid stream in Patented Aug. 20, 1946 VACUUM APPARATUS Kenneth C. D.

Hickman, Rochester, N. Y., as-

signor to Distillation Products, Inc., Rochester, N. Y., a corporation of Delaware Application April 17, 1945, Serial No 588,750

'6 Claims.

This invention relates to improved vacuum apparatus and, in particular, to an improved vacuum pump of the liquid jet type.

In Hickman and Becker U. S. Patent 2,338,583, January 4, 1944, there is described a new type of vacuum pump in which a heated low vapor pressure liquid is ejected transversely through a pumping chamber where the heated ejected liquid stream is partially vaporized so that the vapors and ejected liquid have a common direction and so that both entrain gases to be pumped. The entrained gases are thus forced into a separation chamber where the liquid and vapors are separated from the gases, the gases then being removed from the separation chamber by a vacuum pump.

I have found, in accordance with my invention, that if mean for guiding the vapors given off by such a pump are positioned between the ejected stream of liquid and the walls of the pumping chamber, the pumping action of such a pump is materially improved.

In the following description I have set forth several of the preferred embodiments of my invention, but it is to be understood these are given by way of illustration and not in limitation thereof.

In the accompanying drawings, wherein like numbers refer to like parts;

Fig. .1 is a vertical section of an improved liquid jet pump having a single truncated cone acting as a vapor guiding means positioned between the jet of liquid and the wall of the pumping chamber;

Fig. 2 is a fragmentary enlarged sketch of the pumping chamber illustrated in Fig. l and modified by the provision of a plurality of truncated guiding cones, and;

Fig, 3 is a fragmentary enlarged view showing modified truncated conical guides with thick walls; and

Figs. 4, 5, and 6 are fragmentary enlarged views showing modifications of the throat portion of the diffuser tube.

Referring to Fig. l, numeral 4 designates an elongated pumping chamber of circular cross section provided at its upper enlarged end with a jet nozzle 5 and with an intake conduit 8 for connection to the system to be evacuated (not shown). The lower portion of pumping chamber 4 is provided with a constricted throat It which enters into a spherical separation chamber [2 which is provided with a conduit l4 connected to a backing pump (not shown). Numeral l6 designates a jacket surrounding the lower part of pumping chamber 4 through which cooling fluid is circulated by introduction through conduit I8 and withdrawal through conduit 20. Numeral 22 designates a conduit connected to the lower portion of separating chamber I2 which is connected to a liquid compressor 24 which serves to withdraw relatively low vapor pressure liquid 26 from chamber l2 and to circulate it under high pressure through conduit 28, heating coil 30, valve 32 and jet nozzle 6. Heating coil 30 is heated bymeans of a jacket 34 through is circulated by introduction through conduit 38 and withdrawal through conduit 38. Numeral 40 designates insulating material surrounding heating jacket 34 and conduit 28. Numeral 42 designates a truncated cone which is positioned in pumping chamber 4 so that it is concentric therewith and so that jet 44 passes through the approximate center thereof.

Referring to Fig. 2, numerals -52-56-58-66 and 62 designate a plurality of truncated cones which are positioned centrally within pumping chamber 4 so that the jet of liquid 44 passes centrally therethrough.

Referring to Fig. 3 numeral I50 designates a plurality of thick-walled truncated-cone vaporguiding members. The walls of the guiding members are so shaped that the vapors receive extra expansion as they move downwards.

Referring to Fig. 4, numeral I62 designates a narrow throat portion having parallel sides of appreciable length at the lower part of diffuser tube 4. The residual kinetic energy of the stream is caused to entrain gases in this portion of the pump, and the pumping effect is thus increased. Numeral I64 in Fig. 5 and numeral H36 in Fig. 6 designate modifications of the throat shown in Fig. 4 which have the effect of increasing the entrainment of gases.

In operating the apparatus illustrated in Fig. 1 conduit 8 is connected to the system to be evacuated and conduit I4 is connected to the backing pump (not shown). Cooling liquid is circulated through jacket 16. Heating fluid is circulated through jacket 34. A low vapor pr ssure liquid is introduced into separating chamber i2 and compression pump 24 is actuated. The compressed liquid 26 flows through coil 30 where it is partially heated. The liquid then flows in a stream cooling the valve 32 through jet nozzle 6 and is ejected therefrom velocity to form a liquid stream 44. This liquid is partially vaporized du to the vacuum which exists in pumping chamber 4 and which is produced by the backing pump. The vapors prowhich heating fluid at a relatively high duced from the liquid stream have a high velocity and direction of movement corresponding to that of the liquid jet 44 from which it is derived. Therefore, gases passing through conduit 8 are entrained by the liquid and vapor stream and are forced downwardly into the throat ID. The vapors are condensed on the walls of chamber 4, and this liquid condensate and the remains of the liquid jet flow or pass into separating chamber l2 along with the gases being pumped. The gases are removed through conduit I I by the backing pump, and the liquid collects in chamber l2 and is recycled through the system by pump 24-. Cone 42 apparently provides a local concentration of the vapors derived from liquid jet 44 and, in any event, improves the pumping action.

The apparatus illustrated in Fig. 2 is operated in the same manner. However, due to the provision of a plurality of truncated cones 50 an accentuation of the pumping effect is produced at cones 50-52-56, etc., serving to produce a local concentration of the vapors and to pumping action.

Reference is made to the above noted Hickman improve the and Hecker patent for further details regarding the operation of this type of pump. One advantage of my improvement is that the velocity of the ejected liquid stream need not be as high as described in said patent, although such higher velocities can be used. This is due to the effect of the truncated cones which produce a local concentration of vapors and guide them in the proper direction. Thus, the liquid need be propelled only by a pressure greater than the pressure of the gas which is being pumped. Also, the size of the stream can be large with low velocities, thu increasing the evaporating area and reducing the need for overheating the liquid. Pressures between 50 and 200 pounds per square inch for streams having a diameter of a to 1" are preferred, but higher or lower pressures and smaller or larger diameter streams can b used. My improved pump will operate economically against very high backing pressures.

What I claim is:

1. A vacuum pump adapted to evacute a closed system comprising in combination a closed cham her. a liquid jet nozzle located near one ndof the chamber, and directed toward the opposite end of the chamber, an inlet for gases to be entrained or pumped, which inlet is positioned near to the liquid jet nozzle, means for guiding the vapors given on by the liquid jet which means is positioned so that it is between the liquid jet and the chamber wall, a collecting and separating means for liquid and entrained gases at the end of the chamber opposite to the nozzle, means for compressing and heating actuating liquid, means for conveying compressed and heated liquid to the nozzle for reuse and an exhaust port for removing the entrained gases from the collecting and separating means.

2. A high vacuum pump adapted to evacuate a closed system to a low absolute pressure comprising in combination a closed chamber, a liquid jet nozzle of small aperture located near one end of the chamber, and directed toward the opposite end of the chamber, an inlet for gases to be entrained or pumped, which inlet is positioned near to the liquid jet nozzle, means for guiding the vapors given off by the liquid jet,

so that it is between theliq id jet and the wall ofthe chamber, a collecting and separatingmeans for liquid and entrained gases at the end of the chambe a po 9 the nude aid q eqt s positioned 4 and separating means containing a low vapor pressure liquid, means for compressing such collected liquid, means for heating collected liquid, means for conveying compressed and heated liquid to the nozzle for reuse and an exhaust port for removing the entrained gases from the collecting and separating means.

3. A high vacuum pump adapted to evacuate closed systems to low absolute pressures comprising in combination a closed chamber, a liquid jet nozzle of small apertur located near one end of the chamber, and directed toward the opposite end of the chamber, an inlet for gases to be entrained or pumped, which inlet is positioned near to the liquid jet nozzle, at least one truncated cone vapor-guiding means positioned inside the chamber so that it surrounds the liquid jet and is approximately concentric therewith, a collecting and separating means for liquid and entrained gases at the end of the chamber opposite to the nozzle, said collecting and separating means containing a low vapor pressure organic liquid, means for compressing such collected liquid, means for heating collected liquid, means for conveying compressed and heated liquid to the nozzle for reuse, and an exhaust port for removing the entrained gases from the collecting and separatin means.

4. A high vacuum pump adapted to evacuate closed systems to low absolute pressures comprising in combination a closed chamber, a liquid jet nozzle of small aperture located near one end of the chamber, and directed toward the opposite end of the chamber, an inlet for gases to be entrained and pumped which inlet is positioned near to the liquid jet nozzle, a truncated cone positioned inside the chamber so that it surrounds and is concentric with the liquid jet and so that its smallest end is nearest the nozzle, a collecting and separating means for liquid and entrained gases at the end of the chamber opposite to the nozzle, means for compressing actuating liquid, means for heating compressed actuating liquid, means for conveying compressed and heated liquid to the nozzle for reuse and an exhaust port for removing the entrained gases from the collecting and separating means.

5. A high vacuum pump adapted to evacuate closed systems to low absolute pressures comprising in combination a closed chamber, a liquid jet nozzle of small aperture located near one end of the chamber, and directed toward the opposite end of the chamber, an inlet for gases tolbje entrained or pumped which inlet is positioned near to the liquid jet nozzle, at least one truncated cone positioned inside the chamber so that it surrounds and is concentric with the liquid jet and so that its smallest end is nearest the nozzle, a collecting and separating means for liquid and entrained gases at the end of the chamber opposite to the nozzle, said collecting and separating means containing a low vapor pressur liquid, means for compressing such collected liquid, means for heating collected liquid, means for conveying compressed and heated liquid to the nozzlefor reuse, and an exhaust port for removing the entrained gases from the collecting and separating means. 6. A high vacuum pump adaptedto evacuate closed systems to low absolute pressures comprising in combination a closed chamber, a liquid jet nozzle of small aperture located near one end of the chamber, and directed toward the opposite end of the chamber, an inlet for gases to be entrained or pumped, which inlet is positioned near to the liquid jet nozzle, a plurality of truncated cones positioned in spaced relation inside the chamber so that they urround and are concentric with the liquid jet and so that their smallest ends are nearest the nozzle, a collecting and separating means for liquid and entrained gases at the end' of the chamber opposite to the nozzle, said collecting and separating means containing a low vapor organic pressure liquid, means for compressing such collected liquid, means for heating collected liquid,, means for conveying compressed and heated liquid to the nozzle for reuse, and an exhaust port for removing the entrained gases from the collecting and separating means.

KENNETH C. D. HICKMAN. 

